1. Field of the Invention
The present invention is generally related to an antibiofouling copolymer, and more particularly, an antibiofouling statistical nonionic-zwitterionic copolymer.
2. Description of the Prior Art
Zwitterionic polymers containing the pendant groups of phosphobetaine, sulfobetaine, and carboxybetaine have received growing attention for use in the new generation of blood-contacting materials because of their good plasma protein resistance. In the last several years, poly(sulfobetaine methacrylate) (polySBMA) with a methacrylate main chain and an analogue of the taurine betaine pendant group (CH2CH2N+—(CH3)2CH2CH2CH2SO3−) has become the most widely studied zwitterionic polymer due to its ease of synthetic preparation.
The thermoresponsive (nonionic) polymer undergoes a sharp hydrophilic-hydrophobic transition in water at a temperature, wherein this temperature is called the lower critical solution temperature (LCST). Poly(N-isopropylacrylamide) (polyNIPAAm) is the most widely studied thermoresponsive polymer. However, the solution properties of zwitterionic polymers differ considerably from those of nonionic polymers. In aqueous solution, polySBMA, like other zwitterionic polymers, exhibits an upper critical solution temperature (UCST) that increases with the molar content.
Recently, some research works reported physical micellization of synthesized diblock copolymers with thermoresponsive and zwitterionic properties. These block copolymers were found to exhibit double thermosensitive phase transition of LCST and UCST behaviors in water. However, these studies did not extend to the use or evaluation of these diblock copolymers as biological or biomedical materials.
In fact, there is potential risk for using the block copolymer in bio-application. The above-mentioned block copolymer combines LCST block (thermoresponsive) and UCST (zwitterionic) block. The inside and outside blocks of the micelles can thus be tuned by a simple thermal stimulus. However, the LCST block (thermoresponsive), such as polyNIPAAm, would cause strong adsorption of protein, cell, or bacterial. When the temperature changes and the outside block of a micelle tuned to be LCST block, strong adsorption of bio-molecules may quickly occur on the micelle surface, then may result irreversible aggregates or blocking. It would be especially dangerous to use the block copolymer in blood contacting application.
For the reason that conventional block copolymers with thermoresponsive and zwitterionic properties could probably result in irreversible aggregates or blocking, a need has arisen to propose a novel copolymer suitable for bio-application.